WASHINGTON — A former Iranian deputy defense minister who once commanded the Revolutionary Guard has left his country and is cooperating with Western intelligence agencies, providing information on Hezbollah and Iran's ties to the organization, according to a senior U.S. official.

Ali Rez Asgari disappeared last month during a visit to Turkey. Iranian officials suggested Wednesday that he may have been kidnapped by Israel or the United States. The U.S. official said Asgari is cooperating of his own free will. He did not divulge Asgari's whereabouts.

Asgari served in the Iranian government until early 2005 under then-President Mohammad Khatami. His background suggests that he would have deep knowledge of Iran's national security infrastructure, conventional weapons arsenal and ties to Hezbollah in south Lebanon. Iranian officials said he was not involved in the country's nuclear program, and the senior U.S. official said Asgari is not being questioned about it.

Former officers with Israel's Mossad spy agency said that Asgari had been instrumental in the founding of Hezbollah in the 1980s, around the time of the bombing of the U.S. Marine barracks in Beirut.

Iran's official news agency, IRNA, quoted the country's top police chief, Brig. Gen. Esmaeil Ahmadi-Moqaddam, as saying that Asgari was probably kidnapped by agents working for Western intelligence agencies.

The Israeli newspaper Haaretz reported that Asgari was in the United States. Another U.S. official denied that report and suggested that Asgari's disappearance was voluntary and orchestrated by the Israelis. The Israeli government denied any connection to Asgari. "To my knowledge, Israel is not involved in any way in this disappearance," said Mark Regev, the spokesman for Israel's foreign ministry.